Treatment of metals



Patented Dec. 7, 1943 UNITED STATES PATENT OFFICE TREATMENT OF METALS Wilfred James Clifford and Henry Howard Adams, Brentford, England, assignors to Parker Rust-Proof Company, Detroit, Mich., a. corporation of Michigan No Drawing. Application December 13, 1941, Se-

iialsNo. 422,873. In Great Britain February 4,

9 Claims.

This invention relates to the treatment of metals, especially iron or steel, for instance to the treatment of metals with phosphate coating solutions in order to improve the resistance of cleaned steel sheet for two minutes at 80 C.

The cleaned steel sheet referred to here and in the examples given below is a steel sheet in its original bright rolled condition rendered substantially free from grease by wiping with clean the metals to corrosion or to provide a corrosionwhite spirit.

resisting base for paints. This application is a continuation in part of application, Serial No. Substance Optimum 254,238, filed February 2, 1931, issued September wmwmtim 15, 1942, as Patent No. 2,295,545.

It 1s an obJect of the nvention to accelerate 10 Nitmso N methylutethane the action of reagents which attack a metal surp-Nitr s -dimethylaniljne ,oi fa p-Nitrosophenol 4 It is a further object of the invention to accelerate the action of phosphate coating solu- While the compounds of the i ve t on ay e tions such as zinc, manganese and the like, i. e. the only acc present in the coating bath. to reduce the time taken by the coating solution they may a o be e p oyed n c nj ncti n With to form a complete coating, or to reduce the other accelerators, and with other acid phostemperature, or to obtain a better coating in a phate coat ng solutions. for instance, metallic given time under given conditions than if the accelerato s Such as copp r comp d o icompound were not present, dizing agents such as nitrates or nitrites. The

Where phosphate and similar coatings are bepr sence of c pper i ns appears to promote ing employed, they may be applied to the metal heavier and darker coatings and the presence in any suitable manner, for instance by sprayof a nitrate, such as zinc nitrate, appears to give ing, brushing, flowing or immersion methods. a slight further acceleration.

It has now been found that the action of re- If 0.001% of copper (calculated as the metal) e ts Which attack metal surfaces, and especialis added to the solutiomfor instance in the form ly phosphate coating solutions, are improved by of the nitrate or carbonate, a darker and slightly incorporating therein the nitroso group, heavier coating is obtained, and the addition of As illustrative of the compounds which may zinc nitrate results in a slight further accelerabe employed to provide the nitroso group we o have p-nitrosophenol, p-nitrosodimethylaniline, While the invention has been illustrated y nitroso-n-methylurethane and the like. the treatment of steel, it is also useful in the The optimum concentration of the compound coating of other metallic surfaces, such as surto provide the accelerating group in the reagent faces co ta zinc and a oy thereofattacking the metal surface difiers with different What We claim is: compounds but in the case of phosphate coating A co po t o co p an d p p ate solutions is in general from about .01% to .4% coating solution containing an organic compound by weight of the solution. The proper amount, which contains the nitroso group, said compound of accelerator for bst results may be easily debeing dissolved in the solution in an amount that termined in any case by starting the solution oiT 40 accelerates the coating action of the solution. with a small amount of the accelerator and in- 2. A composition of matter comprising a zinc creasing the amount added to the phosphate dihydrogen phosphate coating solution containcoating solution until the desired acceleration is ing an organic compound containing the nitroso obtained. group, said compound being dissolved in the so- The optimum concentrations, under the conlution in an amount that accelerates the coatditions used, of various compounds which; may ing action of the solution. be employed according to the invention are 3. A composition of matter comprising a mangiVen i t e following table, the results being ganese dihydrogen phosphate coating solution arrived at y adding the pound to a solution containing an organic compound containing the f inc dihydrogen phosphate havin a normalnitroso group, said compound being dissolved in ity of N/2o free acid (determined by titrating the solution in an amount that accelerates the with the aid of methyl orange indicator) and coating actionof the solution.

N/5 total acid (determined by titrating with the 4. The process which comprises treating one. aid of phenolphthalein indicator) and treating a of the group consisting of ferrous and zinciferoua.

surfaces with a phosphate coating solution con taining an organic compound which itself contains a nitroso group, said compound being dissolved in the solution in an amount that accelerates the coating action of the solution until there is obtained upon the metallic surface a visible, protective phosphate coating.

5. The process which comprises treating one of the group consisting of ferrous and zinciferous v urfaces with a phosphate coating solution. containing zinc and an organic compound having the nitroso group, said compound being dissolved in the solution in an amount that accelerates the coating action of the solution until there is obtained upon the metallic surface a visible, protective phosphate coating.

6. The process which comprises treating one of th group consisting of ferrous and zinciferous surfaces with a phosphate coating solutioncontaining manganese and an organic compound having the nitroso group, said compound being dissolved in the solution in an amount that accelerates the coating action of the solution until there is obtained upon the metallic surface a visible, protective phosphate coating.

7. The process which comprises treating a surface of one of the group consisting of ferrous and zinciferous surfaces with a phosphate coating solution containing nitroso-N-methylure. thane, said nitroso-N -methylurethane being dissolved in the solution in an amount that accelerates the coating action of the solution, until a visible, protective phosphate coating is obtained upon the metallic surface. I

8.' The process which comprises treating a surface of one of the group consisting of ferrous and zinciferous surfaces with a phosphate coating solution containing p-nitroso-dimethylaniline, said p-nitroso-dimethylaniline being dissolved in the solution in an amount that accelerates the coating action of the solution, until a visible, protective phosphate coating is obtained upon the metallic surface.

9. The process which comprise treating a surfac of one of the group consisting of ferrous andzinciferous surfaces with a phosphate coating solution containing p-nitroso-phenol, said p-nitroso-phenol being dissolved in the solution in an amount that accelerates thecoating action of the solution, until a visible protective phosphate coating is obtained upon the metallic surface.

WILFRED JAMES CLIFFORD. HENRY HEWARD ADAMS. 

